1. Field of the Invention
The present invention relates to reciprocating motors, and particularly, to a stator of a reciprocating motor and a fabricating method thereof capable of simplifying a fabrication process, and of preventing a dimensional error when using an injection molding.
2. Description of the Conventional Art
A motor converts electrical energy into kinetic energy. Motors are classified into a rotary motor converting electrical energy into a rotary movement is force and a reciprocating motor converting electrical energy into a linear movement force and the like.
FIG. 1 is a lateral cross-sectional view which shows an example of a conventional reciprocating motor. As shown therein, the reciprocating motor includes a stator S having an outer core 100 and an inner core 200 positioned inwardly of the outer core 100, and a mover 300 movable within a gap between the outer core 100 and the inner core 200 of the stator S. The mover 300 includes a permanent magnet 310 and a magnet holder 320 for holding the permanent magnet 310. In the outer core 100, a coil winding 400 is coupled with a bobbin 50 inside of which the coil winding 400 is wound.
The outer core 100 is formed by laminating a plurality of lamination sheets. Each lamination sheet is formed in a “Π” shape (i.e., a “c” or “u” shape) with an open portion 110 between the leg portions thereof being opened inwardly so as to position the coil winding 400 and the bobbin 50 therewith, a base portion 120 positioned on an outer side from the open portion 110 and through which a flux flows, and pole portions 130 extending from both inner ends of the base portion 120 and forming poles.
The inner core 200 is spaced from an inner surface of the outer core 100 by a certain interval, and is formed by laminating lamination sheets of a rectangular shape.
The bobbin 50 is formed in an annular shape, and the coil winding 400 is formed by winding a coil around the bobbin 50 multiple times.
FIG. 2 is an end view showing a reciprocating motor equipped with the stator according to the conventional art.
As shown in the drawing, the outer core of the stator is formed by coupling core blocks LU1 formed by laminating a plurality of radial lamination sheets L1 with a certain thickness to the annular bobbin 50 in the circumferential direction.
An inner surface and an outer surface of each core block LU1 are formed as curved surfaces by the inner and outer edges of the plurality of laminated sheets L1, respectively. The inner surfaces of the core blocks LU1 coupled to the bobbin 50 describe a cylinder, and the outer surfaces thereof maintain certain intervals therebetween.
The bobbin 50 includes an annular body 51 therein in which a winding groove (not shown) of an annular shape is formed in a circumferential direction, and an annular cover 52 covering the winding groove of the annular body 51. The coil winding 400 is located in the winding groove of the annular body 51.
A connection fixing portion 55 of the bobbin 50 has a certain thickness and is formed in a band type with the same width as that of the annular cover 52. The connection fixing portion 55 covers an outer surface of the core blocks LU1, a part of both side surfaces thereof and a part of an outer surface of the bobbin exposed to the exterior between the core blocks LU1. Both side surfaces and the outer surface of the core blocks LU1 are closely adhered with the connection fixing portion 55, and the connection fixing portion 55 is thus extended (protruded) outwardly. That is, the plurality of core blocks LU1 are fixedly-coupled to the bobbin 50 by means of the connection fixing portion 55.
The annular body portion 51 of the bobbin 50 is equipped with a plurality of discharge openings 54 through which humidity is discharged.
A fabrication process of such a stator for a reciprocating motor will be explained herebelow. The bobbin 50 which includes the annular body 51 equipped with the winding groove 53 in an outer circumferential surface thereof is fabricated through a process such as an injection molding process and a cover 52 capable of covering the annular body 51 is fabricated as shown in FIG. 3.
Next, the winding groove 53 of the bobbin 50 is wound with the coated coil 400 therearound multiple times and then the outer circumferential surface of the bobbin 50 is covered with the cover 52.
Afterwards, the core blocks LU1 and LU2 made by laminating a plurality of sheets L1 onto the bobbin 50 are coupled with one another so as to form a cylinder by their inner surfaces, and the outer surfaces thereof are arranged to maintain predetermined intervals therebetween.
The coil winding on which the core block LU1 is arranged is then put into a mold 502, and an over-molding is performed thereon using a die casting method or an injection molding method through an insulator inlet 503. Thus, after completing the outer core 100, the inner core 200 is arranged spaced from an inner circumferential surface of the outer core 100 to thereby obtain a stator.
However, in such a conventionally constructed stator for the reciprocating motor, the bobbin 50 is molded with a plastic material and accordingly it has relatively low strength. As a result, deformation of the bobbin 50 can occur when winding the coil in the winding groove 53 of the bobbin 50, and a wound tension in winding the coil must be adjusted appropriately which disadvantageously makes an assembling process difficult.
Moreover, the stator for the conventional reciprocating motor is fabricated through such processes of winding the coil 400 around the bobbin 50, covering it over with the cover 53, and putting it into the mold 502. As a result, the fabrication processes become complicated and the number of fabrication steps is increased which incurs an increased fabrication cost and a decreased productivity.
In addition, because the injection molding method is used in an over molding process in which the coil winding is coated with an insulating material, the molded object becomes contracted in cooling to thereby cause a dimensional error, and non-uniformity of the product may occur due to a temperature variation of a mold, which increases a defect rate. Also, a temperature of the mold and a pressure condition in an initial molding setting should be set. Therefore, there are several problems such as complicated fabrication processes and an high fabrication cost.